1. Field of the Invention
The present invention relates to a data recording technique, and more particularly to a data recording technique which is capable of indicating such information as an allowable recording time period on a recording medium to a user in case that encoding recording of video and audio data is performed while the amount of data to be recorded per unit of time is varied, i.e., data is recorded at a variable recording rate.
2. Description of the Related Art
Recent advances in digital technology have led to increasing proliferation of digital VTRs in lieu of conventional VTRs. By recording data with a variable-rate encoding method (data encoding method) called MPEG2 (Moving Picture Experts Group Phase 2), it would be possible to achieve long-hour recording on a disc-type recording medium such as a DVD-RAM.
A data recording apparatus such as a VTR for home use is generally employed to record TV programs. In Japanese Unexamined Patent Application No. 20754/1993, for example, there is disclosed a timer operation management apparatus using a technique for adjusting a recording time period so that a preselected TV program can be recorded on a tape. In a conventional VTR or other recording equipment, if the remaining capacity of tape necessary for recording a preselected TV program is found to be insufficient in timer presetting, the timer operation management apparatus proposed in this disclosure automatically recognizes insufficiency of the remaining capacity of tape and selects a proper recording speed to prevent possible non-recording of a part of the preselected TV program.
A technique for detecting the remaining capacity of tape according to such a condition as a change in reel rotating speed is also known.
Further, Japanese Unexamined Patent Application No. 65616/1996, for example, shows a digital recording apparatus and digital recording method for recording/reproducing video and audio data on a recording medium without insufficiency and excessive surplus with respect to the remaining capacity thereof in digital video-audio data recording/playing equipment.
In most of these conventional data recording arrangements, two recording time modes, i.e., standard-time recording mode and long-time recording mode are available. In a TV program recording operation in the standard-time recording mode, if it is judged that the remaining time on tape is to be insufficient for recording a selected TV program, a lower tape running speed or a lower transfer bit rate is taken at and from a certain point in time to set up the long-time recording mode so that the selected TV program can be contained onto the tape currently loaded.
Still further, Japanese Unexamined Patent Application No. 179597/1997 shows an audio data recording apparatus for recording audio data into memory on the principle of variable-length coding, in which an allowable recording time period is indicated through calculation on the remaining capacity of memory and a predicted average coded bit rate.
In a data recording arrangement in which a variable recording rate technique such as MPEG2 is used to encode data for TV program recording on a DVD-RAM or another similar disc serving as a recording medium, for example, the allowable recording capacity of the disc can be indicated in terms of the amount of data easily but it is rather difficult to accurately calculate the amount of time allowable for recording thereon. Since data is recorded at a variable rate, the amount of data recorded per unit of time varies therewith.
It is however required to let a user know an allowable recording time period properly when needed by the user. In data recording at a variable rate, it may also be required to ensure a recording time period desired by the user in addition to mere indication of the remaining time on the disc. Further, there is a need to indicate programmed recording information such as a time period to be taken for recording operation and proper operational information according to the remaining capacity of the disc. Under some operational conditions selected by the user, proper adjustment of an average value representing the amount of data to be recorded per unit of time is also required.
It is therefore an object of the present invention to solve the above-mentioned problems by providing a data recording apparatus and technique wherein an allowable recording time period can be indicated in data recording at a variable rate, alternatives in recording condition setting can be indicated according to the allowable recording time period, and the amount of data to be recorded per unit of time can be adjusted under certain user-selected operational conditions.
In accomplishing this object of the present invention and according to one aspect thereof, there is provided a data recording arrangement comprising:
recording-reading means for recording data on a recording medium while varying the amount of data per unit of time and for reading out the data thus recorded on the recording medium;
calculating means for determining an allowable recording capacity of the recording medium and calculating an allowable recording time period thereon according to the determined allowable recording capacity and the amount of data per unit of time; and
indicating means for indicating the calculated allowable recording time period.
Further, in accordance with another aspect of the present invention there is provided a data recording arrangement comprising:
recording-reading means for recording data on a recording medium while varying the amount of data per unit of time according to recording conditions and for reading out the data thus recorded on the recording medium;
calculating means for determining an allowable recording capacity of the recording medium and calculating an allowable recording time period thereon according to the determined allowable recording capacity and the amount of data per unit of time;
control means for controlling data recording operation according to setup conditions specified through input means;
decision means for determining recording conditions according to the calculated allowable recording time period and the setup conditions specified through the input means; and
indicating means for indicating the calculated allowable recording time period and the determined recording conditions.
Still further, in accordance with another aspect of the present invention, a data recording arrangement, in which data is recorded on a recording medium while the amount of data per unit of time is varied, is provided to include indicating means for presenting an allowable recording time period to be taken for recording data for the longest period of time, an allowable recording time period to be taken for recording data for the shortest period of time, and an allowable recording time period to be taken for recording data on the basis of an average value of the amount of data per unit of time.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.